During normal operating conditions of a hybrid imaging sensor chip assembly (SCA), light is passed through a front-end optical system such that it forms an image incident upon an SCA detector. This incident light on the SCA may be a direct image of a scene or object of interest, or it may be a spectrographic image showing the spectral distribution of energy of a scene or object. The incident light on the SCA is absorbed by the detector and creates an electrical charge within the detector material, which is collected, processed, and passed to external circuitry by a read-out integrated circuit (ROIC).
In some instances, a complementary metal-oxide semiconductor (CMOS) ROIC within a SCA may generate a small, but significant, amount of radiative emission (i.e., “glow”). The radiative emission from CMOS ROICs is a fundamental property of metal-oxide-semiconductor field-effect transistor (MOSFET) operation, and may increase when a large number of transistor devices are used within a CMOS ROIC design. When CMOS ROICs are included within a hybrid imaging device, the undesired radiative emission may be absorbed by the detector, and generate undesired signal and noise, which is then collected by the ROIC. While in some applications the resulting ROIC glow may be negligible, in particular for low optical background scientific imaging applications (e.g., spectroscopy and astronomy applications), the undesired radiative emission can have a significant negative impact on device performance.
In other instances, light or high energy radiation may pass through the detector and arrive at the ROIC. Such an occurrence can negatively impact and impair the functionality of the ROIC. For example, these situations may occur when natural high energy radiation sources, such as those found in space-based applications, man-made laser light sources, and radiation sources produced within or outside of the earth's atmosphere, are directed at the hybrid imaging device. In extreme cases, these conditions may even cause temporary or permanent damage to the SCA.